Trithiocarbonates as plant defoliants



Patented Aug. 19, 1952 E 1 STATES PATEN TRITHIOCAfiBONATESJASPLANT: 7 V 7' 7 DEFOLIANT-S- r men. Goodhue and CarolynEJ TissolfjBartles- ,ville, .0kla., assignors to Phillips" 16 Claims.

This invention relates to the use ofxsulfenyl and 'thiosulfenyl trithiocarbonates as plant defoliating agents.

We have now discovered that sulfenyl and thiosulfenyl trithiocarbonates are efiectiveplant defoliants. These compounds can be represented by the general formula whereinR and R are organicradicals from. the class of alkyl, cycloalkyl, aryl, alkaryl "and-aralkyl groups; m is an integer from the group of 1, 2 and 3; n is an integer vfrom the group of 2 and 3 and R and R, can be different. A method for the production of these'coinpounds when mis 1 alflt iflvz is 2' or 31fromf'the interaction of trit hi o carbonates with an organic sulfurhalidesuch as.

The compounds of the present invention whenm is 3 and n is 3 canbe preparedfrom the-inter- :4: No Drawing... AplplicationfgAp -ilizl.1 9 50, 1

Serial No. 15.7. 102 Y 2 tylsulfenyl trithioarbonate. Typical compounds applicableto the present invention when mu ls 3 and Ends 3 include S tertebutylthiosulfenyl sfa tert octylthiosulfenyl. trithiocarbonate... SrhBXYJ-e thiosu1feny1. 1s- .dodecylthiosulfenyl ;-.-trith-iocar+ bonateandthelike. 1

These compounds are. effective defoli-ants' when applied to plants in any suitable form such as solutions, emulsions;-dusts,:aerosols, fogs and the like, When, fogging. methods are employed temperatureslin fogg ngrat evices "or I the i l I should-notice s'uflic'i'ently elevatedto cause no, i,- ble j de composition.of the present'de'foliants, We have foun'd that it is'i convenientflto applya ithioc'a'rbona'te of the. class disclosed as an aqueous emulsion in the form of a spray. The compounds of the present invention are also advantageously adaptable for application by aircraft asQmechanicaI dispersions or mistsjproduced by high velocity air jet devices. v a "Any; suitable carrierfo'r solvent may be employed which is inert-with" respect to the active defoliating agent and which will not provide a harmful effect on cotton, tomatoes, beans or other crops when applied thereto. Examples of suitable solvents or carriers include straight and branched chain and cyclic parafiinic hydrocarbons containing at least five carbon atoms such as n-pentane, isopentane, cyclohexane, octane and the like or mixtures thereof. Talc, kleselgum and other inert carriers may bev used in preparing dusts. Water may be used advantageaction of a dimetallic trithioearbonateand .an

'alk-yl thiosulfenyl halide V S MSCSM+2RSSX RSSSgSSSR Typicalcompounds applicable to the present invention when mis '1 andn is 2 includesously to form emulsions, of the compounds of the invention for spraying. When preparing aqueous emulsions, wetting or emulsifying agents such as TritonX 100 (alkyl aryl polyether alco- 'laurate polyethylene oxide) and the like are em- .ployed in suificient quantity to stabilize the emulsion. Emulsions containing from one to 10 per cent by weight of the trithiocarbonateare usually preferred.

The defoliants of .the present invention may be applied in any desired concentration. We have found that 5 to-50 pounds of trithiocarbonate per applied to each leaf of young cotton plants. 1 Defoliation was complete in two days.

3 EXAMPLE II The test of Example I was repeated using 'young beans as test plants. Defoliation was complete in two days.

EXAMPLE III A five weight per cent aqueous emulsion of S-ethyl-S'-tert butylsulfenyl trithiocarbonate was prepared using Triton X as an emulsifier at 0.5 per cent. This emulsion was sprayed on cot-12 ton plants until wet, a minimum amount running Five to seven days after apfrom the leaves. plication the formation of abscission'layers at" the base of the leaf petioles was observed and defoliation was complete after 14 days. This compound was particularly outstandingin that" it removed new leaves as they came out after the plants had been sprayed.

v v EXAMPLE IV The experiment of Example III was repeated using S-ethyl-Setert-butyl-thiosulfenyl l trithiocarbonate. Five to seven days afterapplication the formation of abscission layers at the base .01

the leaf petioles was observed and defoliation was complete at the end of 14. days.

A EXAMPLEV Thefexperiment of Example'III was-repeated using S-te'rt-butyI- S'-tert-butylsulfenyl trithlocarbonate. Five toseven days after application the formation of abscission layers at the base of the leaf petioles was observed and defoliation was complete at the end of 14 days. t

EXAMPLE v1 The test of Example III was repeated using S- tert-butylsulfenyl-S'-tert-butylsulfenyl -trithio carbonate. Five to seven days after application the formation of abscission layers at the base of The defoliation effect of S-tertiary-butylsuljenyl-S'-tertiary-butyl trithiocarbonate as a. 25 per cent solution in SoZtrol140 Leaves Removed X Days. Dosage of Solute Ml. it Amman Per Leaf I Treated 2 Days 3 Days 4 Days V EXAMPLE VIII A series of tests Was made on leaves of cotton plants using solutions of S-tertiary-butylsulfenyl- T Sv'-.tertiary-butyl trithiocarbonate in various sol- The per cent column indicates the concentration of S-tertiarybutylsulleny1-S-tertiary-butyl trithiocarbonate in the particular solvent employed. t

EXAMPLE IX A'series of tests was 'made on cotton and bean plants using solutions 'of S-tertiary-butylsu1fenyl- S'-tertia ry-butyl trithiocarbonate in various s01- vents. An aqueous solution of monosodium'cyan amide, a commercial defoliant. wasiin'clude'd for comparative purposes. Results of the'tests are recorded below. p 4

same- I Total treated leaves removed after X days 'Water" 'Mon osodiu m Cyanamide Per Dosage Beans V bottom I cent; ofigllute 2 leaves treated) ileayes treated) 4,

3 5 6 7 3 5 6 7 days days days days days days. days days The per cent'column indicates the concentration of S-terti ry-butylsulfenyl-S tertiary-butyl trithiocarbonate in the particularsolvent employed.

the leaf petioles was observed and defoliation was partially complete at the end of 14 days.

EXAMPLE; II l H S tertiarybutylsulfenyl-S' -tert-butyl trithio carbonate wasapplied as a 25,per,cent solution in Soltrol (an isoparaflinic hydrocarbon fraction boiling in the range 365-410 F.) to the leaves of large cotton plants which were about three months old. These plants, grown in fertilized soil, were about three feet high and had blossomed and set bolls. Results of applying varying dosages are recorded in the table' belowl 1;

The use of a disulfide as a solvent cm this invention is of particular importance in that sol vents which contribute to the :defoliating effect are diflicult to find in. view of the peculiarity ,of defoliation in respect of herbicidal action, Reasonable variation and modification are possiblewithin the scope of the foregoing'disclosure and the appended claims to the invention the essence of which is that sulfenyl andithiosulfenyl trithiocarbonates havelvbeen found tobe effective as plant defoliating agents. i We' claim: 1 f l. A methodof defoliating'a plant which comprises applying to said plant in an" amount ,suffl 5 cientto effect defoliation a compound selected from the group of sulfenyl and thiosulfenyl trithiocarbonates represented by the general formula RS /S n)R wherein R and R are organic radicals from the class of alkyl, cycloalkyl, aryl, alkaryl and aralkyl groups; 111. is an integer from the group of 1, 2 and 3; m is an integer from the group of 2 and 3, and R and R can be different.

2. The method of claim 1 wherein the plant is a cotton plant.

3. The method of claim 1 wherein the plant is a bean plant.

4. A method according to claim 1 wherein the selected compound is applied in the form of an aqueous emulsion.

.5. A method according to claim 4 wherein the emulsion is prepared using an alkyl aryl polyether alcohol.

6. A method according to claim 1 wherein the selected compound is dissolved in an organic sulfide.

'7. A method according to claim 6 wherein said organic sulfide is di-tertiary-octyl disulfide.

8. A method of defoliating a plant which comprises applying to said plant S-tert-butyl-S'- tert-butylsulfenyl trithiocarbonate inan amount sufficient to effect defoliation.

9. A method of defoliating a plant which comprises applying to said plant S-ethyl-S'-tertbutylsulfenyl trithiocarbonate in an amount sufficient to effect defoliation.

10. A method of defoliating a plant which come prises applying to said plant S-ethyl-S'-tertbutylthiosulfenyl trithiocarbonate in an amount sufficient to effect defoliation.

11. A method of defoliating a plant which comprises applying to said plant S-tert-butylsul- RS(m) 'l J S(n) R wherein R and R are organic radicals from the class of alkyl, cycloalkyl, aryl, alkaryl and aralkyl groups; m isan integer from the group of 1, 2 and 3; n is an integer from the group of 2 and 3 and R and R can be different and said compound is dissolved in an organic solvent.

14. A composition according to claim 13 wherein said compound is dissolved in an organic sulfide.

15. A composition according to claim 13 wherein said compoundv is dissolved in a paraffinic hydrocarbon'solvent.

16. A plant defoliating composition comprising as effective ingredients thereof S-tert-butylsulfenyl-S-tert-butylsulfenyl trithiocarbonate and di-tertiary-octyl disulfide. I v

LYLE D. (BrOODH'UE CAROLYN E. 'IISSOL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Arnold 'Dec. 12, 1950 OTHER REFERENCES Annales Agronomiques, J anuary-February 1947, page 90.

Number 

1. A METHOD OF DEFOLIATING A PLANT WHICH COMPRISES APPLYING TO SAID PLANT IN AN AMOUNT SUFFICIENT TO EFFECT DEFOLIATION A COMPOUND SELECTED FROM THE GROUP OF SULFENYL AND THIOSULFENYL TRITHIOCARBONATES REPRESENTED BY THE GENERAL FORMULA 